The investigators said dozens of others leaving the academy at the end of the day's training sessions were injured in the attack.

In a similar attack in May, a suicide bomber with explosives strapped under his uniform killed more than 90 at a military parade in the city – a massacre that alarmed Washington, which is deepening ties with the Middle-Eastern state.

A suicide bomber blew himself up at a military parade rehearsal in Yemen's capital, killing more than 90 soldiers. Msnbc.com's Dara Brown reports.

The Associated Press reported the death toll in Wednesday’s attack as being “at least 10”, quoting a security official. There was no immediate explanation for the discrepancy in the two tolls.

Yemen's government, weakened by an uprising that eventually toppled former leader Ali Abdullah Saleh, has lost control over whole swathes of the country, allowing militants to overrun several towns in the southern province of Abyan.

The United States sees Yemen as a vital front in its global war on Islamic militants and is increasing its military support for the government of President Abd-Rabbu Mansour Hadi.